class Crass::Parser

# File lib/crass/parser.rb, line 140
def initialize(input, options = {})
  unless input.kind_of?(Enumerable)
    input = Tokenizer.tokenize(input, options)
  end

  @depth = 0
  @maximum_depth = options[:maximum_depth] || DEFAULT_MAXIMUM_DEPTH
  @tokens = TokenScanner.new(input)
end

# File lib/crass/parser.rb, line 39
def self.parse_properties(input, options = {})
  Parser.new(input, options).parse_properties
end

# File lib/crass/parser.rb, line 50
def self.parse_rules(input, options = {})
  parser = Parser.new(input, options)
  rules  = parser.consume_rules

  rules.map do |rule|
    if rule[:node] == :qualified_rule
      parser.create_style_rule(rule)
    else
      rule
    end
  end
end

# File lib/crass/parser.rb, line 68
def self.parse_stylesheet(input, options = {})
  parser = Parser.new(input, options)
  rules  = parser.consume_rules(:top_level => true)

  rules.map do |rule|
    if rule[:node] == :qualified_rule
      parser.create_style_rule(rule)
    else
      rule
    end
  end
end

# File lib/crass/parser.rb, line 88
def self.stringify(nodes, options = {})
  nodes  = [nodes] unless nodes.is_a?(Array)
  string = String.new

  nodes.each do |node|
    next if node.nil?

    case node[:node]
    when :at_rule
      string << '@'
      string << node[:name]
      string << self.stringify(node[:prelude], options)

      if node[:block]
        string << '{' << self.stringify(node[:block], options) << '}'
      else
        string << ';'
      end

    when :comment
      string << node[:raw] unless options[:exclude_comments]

    when :simple_block
      string << node[:start]
      string << self.stringify(node[:value], options)
      string << node[:end]

    when :style_rule
      string << self.stringify(node[:selector][:tokens], options)
      string << '{' << self.stringify(node[:children], options) << '}'

    else
      if node.key?(:raw)
        string << node[:raw]
      elsif node.key?(:tokens)
        string << self.stringify(node[:tokens], options)
      end
    end
  end

  string
end

# File lib/crass/parser.rb, line 153
def consume_at_rule(input = @tokens)
  rule = {}

  rule[:tokens] = input.collect do
    rule[:name]    = input.consume[:value]
    rule[:prelude] = []

    while token = input.consume
      node = token[:node]

      if node == :comment # Non-standard.
        next

      elsif node == :semicolon
        break

      elsif node === :'{'
        # Note: The spec says the block should _be_ the consumed simple
        # block, but Simon Sapin's CSS parsing tests and tinycss2 expect
        # only the _value_ of the consumed simple block here. I assume I'm
        # interpreting the spec too literally, so I'm going with the
        # tinycss2 behavior.
        rule[:block] = consume_simple_block(input)[:value]
        break

      elsif node == :simple_block && token[:start] == '{'
        # Note: The spec says the block should _be_ the simple block, but
        # Simon Sapin's CSS parsing tests and tinycss2 expect only the
        # _value_ of the simple block here. I assume I'm interpreting the
        # spec too literally, so I'm going with the tinycss2 behavior.
        rule[:block] = token[:value]
        break

      else
        input.reconsume
        rule[:prelude] << consume_component_value(input)
      end
    end
  end

  create_node(:at_rule, rule)
end

# File lib/crass/parser.rb, line 200
def consume_component_value(input = @tokens)
  return nil unless token = input.consume

  case token[:node]
  when :'{', :'[', :'('
    consume_simple_block(input)

  when :function
    if token.key?(:name)
      # This is a parsed function, not a function token. This step isn't
      # mentioned in the spec, but it's necessary to avoid re-parsing
      # functions that have already been parsed.
      token
    else
      consume_function(input)
    end

  else
    token
  end
end

# File lib/crass/parser.rb, line 225
def consume_declaration(input = @tokens)
  declaration = {}
  value       = []

  declaration[:tokens] = input.collect do
    declaration[:name] = input.consume[:value]

    next_token = input.peek

    while next_token && next_token[:node] == :whitespace
      input.consume
      next_token = input.peek
    end

    unless next_token && next_token[:node] == :colon
      # Parse error.
      #
      # Note: The spec explicitly says to return nothing here, but Simon
      # Sapin's CSS parsing tests expect an error node.
      return create_node(:error, :value => 'invalid')
    end

    input.consume

    until input.peek.nil?
      value << consume_component_value(input)
    end
  end

  # Look for !important.
  important_tokens = value.reject {|token|
    node = token[:node]
    node == :whitespace || node == :comment || node == :semicolon
  }.last(2)

  if important_tokens.size == 2 &&
      important_tokens[0][:node] == :delim &&
      important_tokens[0][:value] == '!' &&
      important_tokens[1][:node] == :ident &&
      important_tokens[1][:value].downcase == 'important'

    declaration[:important] = true
    excl_index = value.index(important_tokens[0])

    # Technically the spec doesn't require us to trim trailing tokens after
    # the !important, but Simon Sapin's CSS parsing tests expect it and
    # tinycss2 does it, so we'll go along with the cool kids.
    value.slice!(excl_index, value.size - excl_index)
  else
    declaration[:important] = false
  end

  declaration[:value] = value
  create_node(:declaration, declaration)
end

# File lib/crass/parser.rb, line 292
def consume_declarations(input = @tokens, options = {})
  declarations = []

  while token = input.consume
    case token[:node]

    # Non-standard: Preserve comments, semicolons, and whitespace.
    when :comment, :semicolon, :whitespace
      declarations << token unless options[:strict]

    when :at_keyword
      # When parsing a style rule, this is a parse error. Otherwise it's
      # not.
      input.reconsume
      declarations << consume_at_rule(input)

    when :ident
      decl_tokens = [token]

      while next_token = input.peek
        break if next_token[:node] == :semicolon
        decl_tokens << consume_component_value(input)
      end

      if decl = consume_declaration(TokenScanner.new(decl_tokens))
        declarations << decl
      end

    else
      # Parse error (invalid property name, etc.).
      #
      # Note: The spec doesn't say we should append anything to the list of
      # declarations here, but Simon Sapin's CSS parsing tests expect an
      # error node.
      declarations << create_node(:error, :value => 'invalid')
      input.reconsume

      while next_token = input.peek
        break if next_token[:node] == :semicolon
        consume_component_value(input)
      end
    end
  end

  declarations
end

# File lib/crass/parser.rb, line 342
def consume_function(input = @tokens)
  @depth += 1

  begin
    # Discard functions nested more deeply than the maximum allowed depth to
    # avoid exhausting the Ruby stack on maliciously nested input.
    return discard_block(input) if @depth > @maximum_depth

    function = {
      :name   => input.current[:value],
      :value  => [],
      :tokens => [input.current] # Non-standard, used for serialization.
    }

    function[:tokens].concat(input.collect {
      while token = input.consume
        case token[:node]
        when :')'
          break

        # Non-standard.
        when :comment
          next

        else
          input.reconsume
          function[:value] << consume_component_value(input)
        end
      end
    })

    create_node(:function, function)
  ensure
    @depth -= 1
  end
end

# File lib/crass/parser.rb, line 383
def consume_qualified_rule(input = @tokens)
  rule = {:prelude => []}

  rule[:tokens] = input.collect do
    while true
      unless token = input.consume
        # Parse error.
        #
        # Note: The spec explicitly says to return nothing here, but Simon
        # Sapin's CSS parsing tests expect an error node.
        return create_node(:error, :value => 'invalid')
      end

      if token[:node] == :'{'
        # Note: The spec says the block should _be_ the consumed simple
        # block, but Simon Sapin's CSS parsing tests and tinycss2 expect
        # only the _value_ of the consumed simple block here. I assume I'm
        # interpreting the spec too literally, so I'm going with the
        # tinycss2 behavior.
        rule[:block] = consume_simple_block(input)[:value]
        break
      elsif token[:node] == :simple_block && token[:start] == '{'
        # Note: The spec says the block should _be_ the simple block, but
        # Simon Sapin's CSS parsing tests and tinycss2 expect only the
        # _value_ of the simple block here. I assume I'm interpreting the
        # spec too literally, so I'm going with the tinycss2 behavior.
        rule[:block] = token[:value]
        break
      else
        input.reconsume
        rule[:prelude] << consume_component_value(input)
      end
    end
  end

  create_node(:qualified_rule, rule)
end

# File lib/crass/parser.rb, line 424
def consume_rules(flags = {})
  rules = []

  while token = @tokens.consume
    case token[:node]
      # Non-standard. Spec says to discard comments and whitespace, but we
      # keep them so we can serialize faithfully.
    when :comment, :whitespace
      rules << token

    when :cdc, :cdo
      unless flags[:top_level]
        @tokens.reconsume
        rule = consume_qualified_rule
        rules << rule if rule
      end

    when :at_keyword
      @tokens.reconsume
      rule = consume_at_rule
      rules << rule if rule

    else
      @tokens.reconsume
      rule = consume_qualified_rule
      rules << rule if rule
    end
  end

  rules
end

# File lib/crass/parser.rb, line 460
def consume_simple_block(input = @tokens)
  @depth += 1

  begin
    # Discard blocks nested more deeply than the maximum allowed depth to
    # avoid exhausting the Ruby stack on maliciously nested input.
    return discard_block(input) if @depth > @maximum_depth

    start_token = input.current[:node]
    end_token   = BLOCK_END_TOKENS[start_token]

    block = {
      :start  => start_token.to_s,
      :end    => end_token.to_s,
      :value  => [],
      :tokens => [input.current] # Non-standard. Used for serialization.
    }

    block[:tokens].concat(input.collect do
      while token = input.consume
        break if token[:node] == end_token

        input.reconsume
        block[:value] << consume_component_value(input)
      end
    end)

    create_node(:simple_block, block)
  ensure
    @depth -= 1
  end
end

# File lib/crass/parser.rb, line 526
def create_node(type, properties = {})
  {:node => type}.merge!(properties)
end

# File lib/crass/parser.rb, line 534
def create_selector(input)
  create_node(:selector,
    :value  => parse_value(input),
    :tokens => input)
end

# File lib/crass/parser.rb, line 542
def create_style_rule(rule)
  create_node(:style_rule,
    :selector => create_selector(rule[:prelude]),
    :children => parse_properties(rule[:block]))
end

# File lib/crass/parser.rb, line 501
def discard_block(input)
  opening = input.current

  stack = [opening[:node] == :function ? :')' : BLOCK_END_TOKENS[opening[:node]]]
  tokens = [opening] # Non-standard. Used for serialization.

  tokens.concat(input.collect do
    until stack.empty?
      break unless token = input.consume

      case token[:node]
      when :'{', :'[', :'('
        stack.push(BLOCK_END_TOKENS[token[:node]])
      when :function
        stack.push(:')')
      when stack.last
        stack.pop
      end
    end
  end)

  create_node(:error, :value => 'maximum-depth-exceeded', :tokens => tokens)
end

# File lib/crass/parser.rb, line 551
def parse_component_value(input = @tokens)
  input = TokenScanner.new(input) unless input.is_a?(TokenScanner)

  while input.peek && input.peek[:node] == :whitespace
    input.consume
  end

  if input.peek.nil?
    return create_node(:error, :value => 'empty')
  end

  value = consume_component_value(input)

  while input.peek && input.peek[:node] == :whitespace
    input.consume
  end

  if input.peek.nil?
    value
  else
    create_node(:error, :value => 'extra-input')
  end
end

# File lib/crass/parser.rb, line 578
def parse_component_values(input = @tokens)
  input  = TokenScanner.new(input) unless input.is_a?(TokenScanner)
  tokens = []

  while token = consume_component_value(input)
    tokens << token
  end

  tokens
end

# File lib/crass/parser.rb, line 592
def parse_declaration(input = @tokens)
  input = TokenScanner.new(input) unless input.is_a?(TokenScanner)

  while input.peek && input.peek[:node] == :whitespace
    input.consume
  end

  if input.peek.nil?
    # Syntax error.
    return create_node(:error, :value => 'empty')
  elsif input.peek[:node] != :ident
    # Syntax error.
    return create_node(:error, :value => 'invalid')
  end

  if decl = consume_declaration(input)
    return decl
  end

  # Syntax error.
  create_node(:error, :value => 'invalid')
end

# File lib/crass/parser.rb, line 620
def parse_declarations(input = @tokens, options = {})
  input = TokenScanner.new(input) unless input.is_a?(TokenScanner)
  consume_declarations(input, options)
end

# File lib/crass/parser.rb, line 628
def parse_properties(input = @tokens)
  properties = []

  parse_declarations(input).each do |decl|
    unless decl[:node] == :declaration
      properties << decl
      next
    end

    children = decl[:value].dup
    children.pop if children.last && children.last[:node] == :semicolon

    properties << create_node(:property,
      :name      => decl[:name],
      :value     => parse_value(decl[:value]),
      :children  => children,
      :important => decl[:important],
      :tokens    => decl[:tokens])
  end

  properties
end

# File lib/crass/parser.rb, line 654
def parse_rule(input = @tokens)
  input = TokenScanner.new(input) unless input.is_a?(TokenScanner)

  while input.peek && input.peek[:node] == :whitespace
    input.consume
  end

  if input.peek.nil?
    # Syntax error.
    return create_node(:error, :value => 'empty')
  elsif input.peek[:node] == :at_keyword
    rule = consume_at_rule(input)
  else
    rule = consume_qualified_rule(input)
  end

  while input.peek && input.peek[:node] == :whitespace
    input.consume
  end

  if input.peek.nil?
    rule
  else
    # Syntax error.
    create_node(:error, :value => 'extra-input')
  end
end

# File lib/crass/parser.rb, line 683
def parse_value(nodes)
  nodes  = [nodes] unless nodes.is_a?(Array)
  string = String.new

  nodes.each do |node|
    case node[:node]
    when :comment, :semicolon
      next

    when :at_keyword, :ident
      string << node[:value]

    when :function
      if node[:value].is_a?(String)
        string << node[:value]
        string << '('
      else
        string << parse_value(node[:tokens])
      end

    else
      if node.key?(:raw)
        string << node[:raw]
      elsif node.key?(:tokens)
        string << parse_value(node[:tokens])
      end
    end
  end

  string.strip
end